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Failure Analysis Experiments
System Level Failure Analysis
Chip Level Failure Analysis
X-RAY Radiographic
FIB for Microcircuit Modification
EMMI Fault Detection
OBRIRCH Fault Detection
Reliabilities Experiment
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Home > Other Testing Service > Failure Analysis Experiments > Chip Level Failure Analysis
Chip Level Failure Analysis
        External Visual Inspection: detects abnormalities/nonconformance in the device leads, package, or package markings. It is conducted either with the unaided eye or a minimum of a 5magnification inspection on the stereomicroscope.
Internal Visual Inspection: refers to the optical examination of a die and internal package post-decapsulation.

Low Magnification Optical Inspection
        A stereomicroscope is used for a low magnification inspection of the die and package. Defects in the bond wires, internal leads, silicon die, and die bonding may be uncovered using this method.

High Magnification Optical Inspection
A metallurgical microscope provides a high magnification image of the die. Defects are easily observed with objective lenses ranging from 5–150magnification.
Curve Trace
This is an electrical measuring instrument that provides information about the electrical characteristics of a device. By applying a voltage to a device pin and measuring the resultant voltage and current, an assumption can be made about the continuity of a pin. Comparisons can be made of a known good device to a failing device. The technique of curve tracing detects open circuits, short circuits, and leaky
device characteristics.
Bench Testing
Under this technique the failing device is electrically stimulated using the necessary bench test equipment.
With the aid of the product data sheets and automatic electrical test data logs, the device is powered up and the failure mode verified accordingly.
Bench testing is the process of characterizing the failure mode of the sample using various bench equipment for exciting the device and measuring its responses. Equipment required for effective failure verification include various power supplies, multimeters, frequency counters, oscilloscopes, curve tracers, break-out boxes, and the like. Sometimes it is also necessary to build a circuit that simulates the application of the customer where the failure was observed.  The idea is to be able to observe the failure of the sample inside the FA lab without an ATE.
X-Ray Analysis
A 125 kV X-ray system is used as part of the package assessment technique that identifies package cracks, severe die cracks, open bond wires, and lifted ball bonds. The system is extremely useful when used in conjunction with acoustic microscopy since lifted bonds and cracked wires may be associated with delaminated portions of a package.
Acoustic Microscopy
The SONIX Acoustic Microscope is a nondestructive method of detecting variations in the physical properties of a package or a die. The operation is based on simple acoustic principles. The devices under examination are placed into a large container of de-ionized water. An ultrasonic transducer is placed near the surface of the device below the water line. The transducer generates a series of high-frequency waves that impinge upon the various package components. Based on the nature of the material the acoustic wave penetrates, a reflected and partially reflected wave is generated and detected by the transducer.

Based on the amplitude and the phases of the reflected waves, the acoustic microscope can detect internal package cracks, die cracks, voids in the die attach, and interface delaminations.
Bake-out provides additional failure mechanism information on an electrically verified failure. A typical bake-out condition is 24 hours at 256C in an unbiased environment.
This technique refers to a biasing operation at 125C, sometimes used to recreate a failure mechanism.
Burn-in accelerates the normal operating life of a device.

This procedure is undertaken when all applicable nondestructive analysis has been performed. Chemical decapsulation is the package opening method most used throughout ADI. The decapping system uses hot nitric acid to chemically etch plastic packages for internal package inspection.
The mechanical decapping method is used less often and is performed utilizing mechanical decapping tools on hermetic and plastic packages. It is viewed as destructive, depending on the package type.
Emission Microscopy
The Hypervision Emission Microscope is an invaluable piece of equipment in the product analysis lab.
It enables the location of sublayer defects through detection of faint light levels emitted from silicon device structures. These faint light levels arise from recombinant radiation emitted from p–n junctions and from oxides.
Liquid Crystal Analysis
Liquid crystal is a technique used for the localization of current-conducting failure sites (polysilicon-tosubstrate shorts, polysilicon-to-metal shorts), commonly referred to as “hot-spots.” The crystal changes color with the heat increase from a short circuit; the point where the color starts to change is the failure site.
Electrical Microprobing
This is used to trace signals through a device to locate the electrical cause of failure. Microprobing is performed with a probe station along with any of the necessary electrical bench test equipment needed to operate the device.
The prober shown in Figure 62 is a combined manual and automatic submicron probing system and is equipped with laser-cutting and ablation techniques.

Dry Deprocessing
This technique uses a combination of gases to etch passivation and dielectrics. A plasma is generated using various ratios of sulfur hexafluoride, oxygen, and carbon tetra fluoride. While under certain conditions of temperature, RF bias, and pressure they chemically and mechanically etch away the aforementioned layers.
Scanning Electron Microscopy
The SEM is a useful internal inspection tool. By aiming a beam of electrons at the sample surface, results are compiled of the electron beam interaction with the surface to form a surface image. Certain SEM applications use the beam to electrically stimulate the device. These techniques are Electron Beam Induced Current (EBIC), Voltage Contrast, Charge Induced Voltage Alteration (CIVA), and Resistive Contrast Imaging (RCI).
Chemical Deprocessing
This is a chemical wet-bench technique that refers to the removal of individual die layers to expose each layer for inspection and thus isolate the fault within specific layers.
Energy Dispersive X-Ray (EDX)
EDX is a technique used in conjunction with the SEM to qualitatively and/or quantitatively determine the elemental composition of a sample (atomic number 5 or higher). It is useful in cases where a contaminant is suspected.
Cross-Sectioning Techniques
Encapsulated and nonencapsulated cross-sectioning are the two main cross-sectioning techniques employed by ADI.
The encapsulated method requires the failing unit to be set in an epoxy solution and mounted on a cross-sectioning wheel. The unit is then ground to the required location using diamond-polishing sheets and polished off using colloidal silicate. The combined Buehler grinder polisher is shown in Figure 66.
In the nonencapsulated method the die is removed from the package and mounted on a cross-sectioning stub. Again the cross-sectioning tool is used to grind the die back to the defect site.
FIB Cross-Sectioning
The Focused Ion Beam (FIB) system is ADI’s most advanced method of cross-sectioning. It uses a finely focused beam of gallium ions to selectively remove layers of a device. It has many applications for the purposes of failure analysis including precision cross-sections through defect locations. It cuts through interconnects and deposition of tungsten probe pads to isolate failures and allow electrical characterization.
Deposition of tungsten interconnects to implement circuit fixes
Fluorescent Microthermal Imaging (FMI)
This technique is currently under development within ADI. It is a thermal imaging technique that relies on the temperature dependence of an inorganic film to locate failure sites. It will be used as an alternative to liquid crystal analysis.